ALSA: echoaudio: read past end of array

We need to cap "ucontrol->id.index / num_busses_in(chip)" so the we
don't read beyond the end of the array.

I also adding a check on "in" and changing the type in
snd_echo_mixer_put() from short to unsigned int. Those changes are done
for symmetry and are cosmetic.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 10 insertions, 6 deletions

diff --git a/sound/pci/echoaudio/echoaudio.c b/sound/pci/echoaudio/echoaudio.c
index a962de03ebb6..862db9a0b041 100644
--- a/sound/pci/echoaudio/echoaudio.c
+++ b/sound/pci/echoaudio/echoaudio.c
@@ -1283,12 +1283,14 @@ static int snd_echo_mixer_info(struct snd_kcontrol *kcontrol,
 static int snd_echo_mixer_get(struct snd_kcontrol *kcontrol,
                               struct snd_ctl_elem_value *ucontrol)
 {
-        struct echoaudio *chip;
+        struct echoaudio *chip = snd_kcontrol_chip(kcontrol);
+        unsigned int out = ucontrol->id.index / num_busses_in(chip);
+        unsigned int in = ucontrol->id.index % num_busses_in(chip);
 
-        chip = snd_kcontrol_chip(kcontrol);
-        ucontrol->value.integer.value[0] =
-                chip->monitor_gain[ucontrol->id.index / num_busses_in(chip)]
-                        [ucontrol->id.index % num_busses_in(chip)];
+        if (out >= ECHO_MAXAUDIOOUTPUTS || in >= ECHO_MAXAUDIOINPUTS)
+                return -EINVAL;
+
+        ucontrol->value.integer.value[0] = chip->monitor_gain[out][in];
         return 0;
 }
 
@@ -1297,12 +1299,14 @@ static int snd_echo_mixer_put(struct snd_kcontrol *kcontrol,
 {
         struct echoaudio *chip;
         int changed,  gain;
-        short out, in;
+        unsigned int out, in;
 
         changed = 0;
         chip = snd_kcontrol_chip(kcontrol);
         out = ucontrol->id.index / num_busses_in(chip);
         in = ucontrol->id.index % num_busses_in(chip);
+        if (out >= ECHO_MAXAUDIOOUTPUTS || in >= ECHO_MAXAUDIOINPUTS)
+                return -EINVAL;
         gain = ucontrol->value.integer.value[0];
         if (gain < ECHOGAIN_MINOUT || gain > ECHOGAIN_MAXOUT)
                 return -EINVAL;